Process of making manganates



HARRY MGCORMACK,

UNITED srxras PATENT orrrcn.

CHICAGO, OF CHICAGO,

OF CHICAGO, ILLINOIS, ASSIGNOR TO RESEARCH LABORATORY OF ILLINOIS, A CORPORATION OF ILLINOIS.

PROCESS OF MAKING MANGANATES.

No Drawing.

. a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Processes of Making Manganates, of which the following is a specification.

This invention relates to improvements in processes of making manganates, and relates articularly to an improved process of ma ing manganates of the alkali metals, '5. 6., potassium and sodium.

The principal objects of the invention are to provide an improved process'for the making of a manganate as an initial step in the preparation of the permanganate; to provide an improved process for separating said man anate from the other products resulting rom the said initial step; to provide an improved process whereby a substantially pure permanganate is secured without recrystallization; to provide a process which shall be economical in the consumption of raw materials and shall incidentall be such that caustic remaining as a res t of the process is recovered as a byproduct; to provide an improved process in which caustic alkali and manganese dioxid may be treated without the use of an oxidizing agent, such as a nitrate or a chlorate; and, in general, to provide an improved and economical process of the character referred to.

Describing the process in a general way, I first make a strong hydrous solution of caustic alkali and manganese dioxid, evaporate the solution to dryness, stirring meantimeso that the resultin product is a dry pulverulent material, su sequentl heating this material to a comparatively igh temperature. The material so produced is redissolved in water, adding thereto a small quantity of caustic lime, the solution then being boiled vigorously several hours, after which the solids are filtered out. The solution is then concentrated to a specific gravity of about 1.4.

. Upon cooling the above solution, the manganate crystallizes out, and these 0 stals are then separated from the motherhquor. The manganate crystals are next placed in cold water and the water is gradually heated to the boiling point. While the crystals are being dissolved, an oxidizing agent such as chlorin is gradually added to the solution Specification of Letters Patent.

Patented Apr. 20, 1920.

Application filed January 6, 1919. Serial 1%. 269,740.

in such regulated quantities that by-the time the boiling point is reached, the chlorin will have oxidized the manganate to permanganate.

Instead of oxidizing by means of chlorin in the above described manner, the solution may be oxidized by the use of carbon dioxid or by electrolyzing the slightly alkaline solution, or by any other known equivalent oxidizing agent or process.

The resulting liquid, which contains the permanganate in solution, is subsequently concentrated to the desired specific gravity, in the case of permanganate of sodium, and the process is completed; or, if dealing with permanganate of potassium, the solution is concentrated to a specific gravit of about concentrated solution of caustic soda in the proportion of 80 pounds of MnO to each one hundred (100) pounds of caustic. The addition of MnO is effected while the solution is in a fusion kettle which is heated, the heating being continued with repeated stirring until the mass has become pasty. The stirring is continued more and more vigorously as the moisture is driven off so as to breakup all lumps of material, and the heating is continued until the moisture has entirely evaporated, leaving the material in the condition of a dry pulverulent mass. The temperature is then raised to approximately 450 C. and the heating is continued until the end of approximately eight hours from the time the heat was first applied. At this time the mass will be in- 1.2 hot, and subsequently cooled in order to cipiently fused and in a somewhat pasty condition.

The fusion is now transferred to the soluthen concentrated, preferably in a direct heated open pan to a specific gravity of about 1.4. It is then cooled, whereupon the sodium manganate crystallizes in placed'in about six times their weight-of cold water, chlorin beingpassed into the solution while the crystals are dissolving. Heat is applied and the solution brought to boiling, the flowof chlorin being continued and so regulated that by the time the solution is brought to boiling, the. contained sodium manganate will have been oxidized to sodium permanganate. The \solutioncontaining the sodium permanganate is then concentrated in the usual manner until it has the desired specific gravity.

It will be understood that the above described details of the process are merely illustrative of'a specific application of my invention, the scope of which should be determined by claims.

I claim 1.' The improvement in the process of making an alkalinetalmanganate, which solving the resultant material in reference to the appended consists in adding manganese 'dioxid to a consists in adding manganese .dioxid to a hydrous solution of the alkali-metal hydroxid, evaporating said solution to dryness and heating to incipient fusion, diswater, separating the solids and so producing a clear liquid, cooling said liquor and separating therefrom the resulting crystaIs of manganate.

3. The improvement in the process of making an alkali-metal manganate, which consists in adding manganese dioxid to a hydrous solution of the alkali-metal hydroxid, evaporating said solution to dryness and heating to-incipient fusion, dissolving the resultant material in water, converting any carbonate present into hydroxid, separating the solids and so producing a clear liquor, cooling said liquor and separating therefrom the resulting crystals HARRY MoCORMAOK.

of manganate. 

